Histidine (symbol His or H) is an essential amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated –NH3+ form under biological conditions), a carboxylic acid group (which is in the deprotonated –COO− form under biological conditions), and an imidazole side chain (which is partially protonated), classifying it as a positively charged amino acid at physiological pH. Initially thought essential only for infants, it has now been shown in longer-term studies to be essential for adults also. It is encoded by the codons CAU and CAC.
In organic chemistry, an imino acid is any molecule that contains both imine (>C=NH) and carboxyl functional groups.
1-Aminocyclopropane-1-carboxylic acid (ACC) is a disubstituted cyclic α-amino acid in which a cyclopropane ring is fused to the Cα atom of the amino acid. It is a white solid. Many cyclopropane-substituted amino acids are known, but this one occurs naturally. Like glycine, but unlike most α-amino acids, ACC is not chiral.
Pyridoxal phosphate (PLP, pyridoxal 5'-phosphate, P5P), the active form of vitamin B6, is a coenzyme in a variety of enzymatic reactions. The International Union of Biochemistry and Molecular Biology has catalogued more than 140 PLP-dependent activities, corresponding to ~4% of all classified activities. The versatility of PLP arises from its ability to covalently bind the substrate, and then to act as an electrophilic catalyst, thereby stabilizing different types of carbanionic reaction intermediates.
In molecular biology, biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products in living organisms. In biosynthesis, simple compounds are modified, converted into other compounds, or joined to form macromolecules. This process often consists of metabolic pathways. Some of these biosynthetic pathways are located within a single cellular organelle, while others involve enzymes that are located within multiple cellular organelles. Examples of these biosynthetic pathways include the production of lipid membrane components and nucleotides. Biosynthesis is usually synonymous with anabolism.
Homoserine (also called isothreonine) is an α-amino acid with the chemical formula HO2CCH(NH2)CH2CH2OH. L-Homoserine is not one of the common amino acids encoded by DNA. It differs from the proteinogenic amino acid serine by insertion of an additional -CH2- unit into the backbone. Homoserine, or its lactone form, is the product of a cyanogen bromide cleavage of a peptide by degradation of methionine.
Amino acid synthesis is the set of biochemical processes by which the amino acids are produced. The substrates for these processes are various compounds in the organism's diet or growth media. Not all organisms are able to synthesize all amino acids. For example, humans can synthesize 11 of the 20 standard amino acids. These 11 are called the non-essential amino acids).
Purine metabolism refers to the metabolic pathways to synthesize and break down purines that are present in many organisms.
1-Pyrroline-5-carboxylic acid is a cyclic imino acid. Its conjugate base and anion is 1-pyrroline-5-carboxylate (P5C). In solution, P5C is in spontaneous equilibrium with glutamate-5-semialdhyde (GSA).
In molecular biology, the protein domain Saccharopine dehydrogenase (SDH), also named Saccharopine reductase, is an enzyme involved in the metabolism of the amino acid lysine, via an intermediate substance called saccharopine. The Saccharopine dehydrogenase enzyme can be classified under EC 1.5.1.7, EC 1.5.1.8, EC 1.5.1.9, and EC 1.5.1.10. It has an important function in lysine metabolism and catalyses a reaction in the alpha-Aminoadipic acid pathway. This pathway is unique to fungal organisms therefore, this molecule could be useful in the search for new antibiotics. This protein family also includes saccharopine dehydrogenase and homospermidine synthase. It is found in prokaryotes, eukaryotes and archaea.
In enzymology, an L-amino acid oxidase (LAAO) (EC 1.4.3.2) is an enzyme that catalyzes the chemical reaction
In enzymology, a L-pipecolate oxidase (EC 1.5.3.7) is an enzyme that catalyzes the chemical reaction
In enzymology, a saccharopine dehydrogenase (NADP+, L-glutamate-forming) (EC 1.5.1.10) is an enzyme that catalyzes the chemical reaction
In enzymology, glutamate-prephenate aminotransferase is an enzyme that catalyzes the chemical reaction
Pipecolic acid (piperidine-2-carboxylic acid) is an organic compound with the formula HNC5H9CO2H. It is a carboxylic acid derivative of piperidine and, as such, an amino acid, although not one encoded genetically. Like many other α-amino acids, pipecolic acid is chiral, although the S-stereoisomer is more common. It is a colorless solid.
The α-aminoadipate pathway is a biochemical pathway for the synthesis of the amino acid L-lysine. In the eukaryotes, this pathway is unique to the higher fungi and the euglenids. It has also been reported from bacteria of the genus Thermus.
UDP-4-amino-4,6-dideoxy-N-acetyl-beta-L-altrosamine transaminase is an enzyme with systematic name UDP-4-amino-4,6-dideoxy-N-acetyl-beta-L-altrosamine:2-oxoglutarate aminotransferase. This enzyme catalyses the following chemical reaction
Glutamate 2,3-aminomutase is an enzyme that belongs to the radical s-adenosyl methionine (SAM) superfamily. Radical SAM enzymes facilitate the reductive cleavage of S-adenosylmethionine (SAM) through the use of radical chemistry and an iron-sulfur cluster. This enzyme family is implicated in the biosynthesis of DNA precursors, vitamin, cofactor, antibiotic and herbicides and in biodegradation pathways. In particular, glutamate 2,3 aminomutase is involved in the conversion of L-alpha-glutamate to L-beta-glutamate in Clostridium difficile. The generalized reaction is shown below:
D-Amino acids are amino acids where the stereogenic carbon alpha to the amino group has the D-configuration. For most naturally-occurring amino acids, this carbon has the L-configuration. D-Amino acids are occasionally found in nature as residues in proteins. They are formed from ribosomally-derived D-amino acid residues.
In organic chemistry, secondary amino acids are amino acids which do not contain the amino group −NH2 but is rather a secondary amine. Secondary amino acids can be classified to cyclic acids, such as proline, and acyclic N-substituted amino acids.
